Glasgow | 25 SDC NOV | Katarzyna Kazimierczuk | Sprint 2 | linked list

.gitignore

@@ -2,3 +2,4 @@
 node_modules
 .venv
 __pycache__
+package-lock.json

Sprint-2/implement_linked_list/linked_list.py

@@ -0,0 +1,56 @@
+# //operations
+# `push_head` should add an element to the start of the list. 
+# It should return something that can be passed to `remove` to 
+# remove that element in the future.
+
+
+
+# `pop_tail` should remove an element from the end of the list.
+# * `remove` takes a handle from `push_head`, 
+# and removes that element from the list.
+class Node:
+    def __init__(self, data):
+        self.data = data
+        self.next = None
+        self.previous = None
+
+class LinkedList:
+    def __init__(self):
+        self.head = None
+        self.tail=None
+
+    def push_head(self, item_to_insert):
+        # //wrap item to insert in {}
+        wrapped_item = Node(item_to_insert)
+
+        if not self.head:
+            self.head = self.tail = wrapped_item
+        else:
+            wrapped_item.next = self.head
+            self.head.previous = wrapped_item
+            self.head = wrapped_item
+
+        return wrapped_item
+
+    def remove(self, id_for_this_particular_item):
+        node_to_remove = id_for_this_particular_item
+
+        if node_to_remove.previous:
+            node_to_remove.previous.next = node_to_remove.next
+        else:
+            self.head = node_to_remove.next
+
+        if node_to_remove.next:
+            node_to_remove.next.previous = node_to_remove.previous
+        else:
+            self.tail = node_to_remove.previous
+
+        #save data here
+        saved_data = node_to_remove.data
+        node_to_remove.next = node_to_remove.previous = None
+        return saved_data
+
+    def pop_tail(self):
+        if not self.tail:
+            return None
+        return self.remove(self.tail)